Function transformDeleteStmt

src/backend/parser/analyze.c:539–619

* transformDeleteStmt - * transforms a Delete Statement */

 *	  transforms a Delete Statement
 */
static Query *
transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt)
{
	Query	   *qry = makeNode(Query);
	ParseNamespaceItem *nsitem;
	Node	   *qual;

	qry->commandType = CMD_DELETE;

	/* process the WITH clause independently of all else */
	if (stmt->withClause)
	{
		qry->hasRecursive = stmt->withClause->recursive;
		qry->cteList = transformWithClause(pstate, stmt->withClause);
		qry->hasModifyingCTE = pstate->p_hasModifyingCTE;

		/*
		 * Since GPDB currently only support a single writer gang, only one
		 * writable clause is permitted per CTE. Once we get flexible gangs
		 * with more than one writer gang we can lift this restriction.
		 */
		if (pstate->p_hasModifyingCTE)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("writable CTE queries cannot be themselves writable"),
					 errdetail("Apache Cloudberry currently only support CTEs with one writable clause, called in a non-writable context."),
					 errhint("Rewrite the query to only include one writable clause.")));
	}

	/* set up range table with just the result rel */
	qry->resultRelation = setTargetTable(pstate, stmt->relation,
										 stmt->relation->inh,
										 true,
										 ACL_DELETE);
	nsitem = pstate->p_target_nsitem;

	/* there's no DISTINCT in DELETE */
	qry->distinctClause = NIL;

	/* subqueries in USING cannot access the result relation */
	nsitem->p_lateral_only = true;
	nsitem->p_lateral_ok = false;

	/*
	 * The USING clause is non-standard SQL syntax, and is equivalent in
	 * functionality to the FROM list that can be specified for UPDATE. The
	 * USING keyword is used rather than FROM because FROM is already a
	 * keyword in the DELETE syntax.
	 */
	transformFromClause(pstate, stmt->usingClause);

	/* remaining clauses can reference the result relation normally */
	nsitem->p_lateral_only = false;
	nsitem->p_lateral_ok = true;

	qual = transformWhereClause(pstate, stmt->whereClause,
								EXPR_KIND_WHERE, "WHERE");